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Abstract：
Recently, Mn-doped semiconductor nanocrystals (NCs) with high brightness, long lifetimes, and low-energy excitation are emerging for time-resolved luminescence biosensing/imaging. Following our previous work on Mn-doped NCs, in this work we developed poly(styrene-co-maleic anhydride) (PSMA)-encapsulated Mn-doped AgZnInS/ZnS NCs as signal transducers for immunoassay of capsular polysaccharide (CPS), a surface antigen and also a biomarker of Burkholderia pseudomallei which causes a fatal disease called melioidosis. To enhance the assay sensitivity, a surface treatment for PSMA-encapsulated NCs (NC-probes) was performed to promote the presence of carboxyl groups that help conjugate more anti-CPS antibodies to the surface of NC-probes and thus enhance bioassay signals. Meanwhile, time-resolved reading on the luminescence of NC-probes was adopted to minimize the assay background autofluorescence. Both strategies essentially enhance the assay signal-to-background ratio (or equivalently the assay sensitivity) by increasing the signal and decreasing the background, respectively. Through performing and comparing immunoassays with different NC-probes (with and without surface treatment) and different signal reading methods (time-resolved reading and non-time-resolved reading), it was proven that the immunoassay adopting surface-treated NC-probes and time-resolved reading achieved a lower limit-of-detection (LOD) than the ones adopting non-surface-treated NC-probes or non-time-resolved reading. Moreover, the achieved LOD is comparable to the LOD of immunoassay using enzyme horseradish peroxidase as a signal transducer.
摘要：
最近,具有高亮度的Mn掺杂半导体纳米晶体(NCs),寿命长,和低能量激发正在出现用于时间分辨发光生物传感/成像。根据我们先前对Mn掺杂的NC的研究，在这项工作中，我们开发了聚（苯乙烯-共-马来酸酐）（PSMA）封装的Mn掺杂的AgZnInS/ZnSNCs作为荚膜多糖（CPS）免疫测定的信号转导，一种表面抗原，也是伯克霍尔德氏菌的生物标志物，它导致一种致命的疾病，称为类lioidosis。为了提高测定灵敏度，对PSMA包封的NC(NC-探针)进行表面处理以促进羧基的存在,这有助于将更多的抗CPS抗体缀合至NC-探针的表面,从而增强生物测定信号。同时,采用NC探针发光的时间分辨读数，以最大程度地减少测定背景自发荧光。两种策略都通过增加信号和降低背景来实质上增强测定信号背景比（或等效地提高测定灵敏度）。分别。通过使用不同的NC探针（有和没有表面处理）和不同的信号读取方法（时间分辨读数和非时间分辨读数）进行和比较免疫测定，事实证明，采用表面处理的NC探针和时间分辨读数的免疫测定比采用非表面处理的NC探针或非时间分辨读数的免疫测定具有更低的检测限（LOD）。此外，获得的LOD与使用辣根过氧化物酶作为信号转导的免疫测定的LOD相当。
